Modular cabling system

ABSTRACT

A flexible flat cable having a plurality of parallel conductors arranged on an insulating support and covered by an insulating layer is provided with openings formed in the insulating layer located at regular intervals along the cable length. The portions of the cable having the openings are formed into connectors at the user&#39;&#39;s site, or connectors are provided, one at each of the openings, to produce a modular cable which may be separated into usable lengths.

United States Patent [191 Kassabgi I MODULAR CABLING SYSTEM [75]Inventor: Georges Kassabgi, Paris, France [73] Assignee: HoneywellInformation Systems, Italia, Caluso, Italy [22] Filed: Mar. 10, 1971[21] App1.No.: 122,716

[30] Foreign Application Priority Data Mar. 12, 1970 Italy ..2l815 A/7O[52] US. Cl ..339/17 F, 174/117, 339/99 R [51] Int. Cl. ..I-I01r 11/20,l-lOSk 1/02 [58] Field of Search ..339/17, 18, 174,

[56] References Cited UNITED STATES PATENTS 3,239,916 3/1966 Love..339/l7 F X 3,102,767 9/1963 Schneck ..339/l7 F X 3,158,421 l1/l964Hasenhauser, Jr. ..339/1 7 F X 3,088,090 4/1963 Cole et a1 ..339/l7 F3,319,216 5/1967 McCullough... ..339/l7 F X 3,226,473 12/1965 Dahlgren..174/1 17.1 1

[ 51 Apr. 17, 1973 3,211,096 ll/1965 Casghan ..339/l76 MF 3,365,694l/1968 Parker ..39/17 F- 3,l73,991 3/1965 Breakfield, Sr... ..29/6253,393,392 7/1965 Shelley ....339/17 F 3,434,093 3/1969 Wedekind ..339/17F FOREIGN PATENTS OR APPLICATIONS 1,496,312 8/1967 France ..339/l7F1,222,758 H1960 France ..339/l74 Primary Examiner-Marvin A. ChampionAssistant Examiner--Terrell P. Lewis Attorney-Fred Jacob, Ronald T.Reiling and Lewis P. Elbinger ABSTRACT 2 Claims, 10 Drawing Figures IPATENTEUAPRIYIQR g I ',72 51 suguinra PRIOR ART Q FIG. 2

PRIOR ART FIG. 4'

INVEN'I'UR.

ATTORNEY.

PATENTED-APRIYW 3.728.661

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INVENTOR.

BY A TTORNE).

MODULAR CABLING SYSTEM BACKGROUND OF THE INVENTION The present inventionrelates to a modular connection system for electronic devices. Moreparticularly, the present invention relates to a modular connectionsystem for data processing electronic systems, which employs flexibleflat cables for the connection of distinct units in the system.

It is known that in modern data processing systems several electronicsignals may be transferred simultaneously from one unit to the other andthat a plurality of wires are needed for this purpose. In addition tothis, the signals to be transmitted are often pulses having arectangular shape, i.e. with leading and trailing edges which areextremely steep, the pulses being sent with extremely high repetitionrates, of the order of megacycles. In order to avoid attenuations,distortions and mutual couplings between adjacent wires it is thereforeoften necessary to use coaxial shielded wires which are cumbersome and,when collected in a single cable, become mechanically rigid anddifficult to arrange in conduits.

The systems installation at the customer site therefore becomes costly,requiring a large amount of time and making use of cables previouslyprepared in convenient lengths provided with factory prepared terminalconnectors. A quality connection between the cables and connectors is infact essential whether it is accomplished by soldering or by crimpingoperations, to insure the correct performance of the system, and toprevent introducing malfunctions which are generally intermittent andwhose origins are extremely difficult to identify. The cables aretherefore prepared at the factory in required lengths and undergosuitable tests before being sent to their respective users.

Inconvenience is caused by the foregoing in that for every installedsystem it is necessary to define the configuration and the length andarrangement of connection cables, in order to thus provide for theirpreparation, or it is necessary to plan for storing a large number ofpreviously prepared cables of different lengths and types, to be chosenaccording to the needs imposed by any circumstance. Besides theinconvenience and the handling costs deriving from it, if the electronicsystem configuration is to be modified to add, replace, or remove someelectronic units, it will generallyv be necessary to replace theconnection cables which requires that the system be out-of-service forlong periods of time, due to the period required for the changes.

In order to avoid at least in part the inconveniences mentioned the useof flat cables in which the conductor wires are arranged one parallel tothe other on an insulating flexible support shaped as a tape has beenproposed and is now being implemented. These cables present a sectionwith a very low moment of inertia to flexure in the direction normal tothe plane of the cable, and are therefore capable of assuming bends withvery short curve radii. The installation of these cables is much easierthan the cylindric cables. The inconveniences, already mentioned,however, related to the 'need of laboratory preparation and testing andsubsequent installation, handling spare parts, possible need forreplacement cables, are still present.

A further aspect to be put in evidence, and one which forms a seriousinconvenience for the connection cables used up to now, whether they areflat or not, concerns the so called bus" connections which are largelyused in the connection into a system of several units, generally of thesame type. The bus" connec-v tion, compared to the star" connection, ischaracterized in that a certain group of wires interconnect severaldistinct units in sequence; for example, a controller device may beconnected to several magnetictape handlers. A group of wires isconnected at one end, by means of a connector to the controller deviceand at the other end by means of a connector, to the first tape handler.The cable end connector enters on an input connector set on the firsttape handler; suitable jumpers connect the input connector to an outputconnector. A second group of wires, forming a second cable is connectedby means of a connector to the output connector of the first tapehandler and at the other end, always by means of a connector, to asecond tape handler. The second tape handler, also has an outputconnector, connected, by means of jumpers, to the input connector, andtherefore it is possible to accomplish a cascade connection with a thirdtape handler and subsequently to a fourth and so on, up to a maximumnumber limited in general by the signal transfer time along the cable.For the correct performance of the devices, the signal transfer timecannot exceed a certain value and therefore imposes a limit to the totallength of the bus connected cables. In a connection of this type it isevident that the probability of a bad contact between connectors, withsubsequent introduction of malfunctions doubles with each added unit,and in correlation, the reliability of the connection decreases.

An object of the present invention is to eliminate the inconveniencesmentioned by providing the flat cable modular connection system, whichis characterized in the factory and to subsequent tests, the normalcontinuous manufacturing tests being sufficient.

BRIEF DESCRIPTION OF THE DRAWINGS These and further advantages willbe'explained by the following description which is given by way ofexample and not limitations when taken with reference to the encloseddrawings in which:

FIG. I shows a flexible flat cable structure known in the state of theart;

FIG. 2 shows a terminal connection method, known in the state of theart, employed for a flexible flat cable of the type shown in FIG. I;

FIG. 3 represents the structure of a second type of flexible flat cableknown in the state of the art;

FIG. 4 represents a terminal connector, known in the state of the art,employed for a flexible flat cable of the type as per FIG. 3;

FIG. 5 represents schematically a preferred form of embodiment of aflexible flat cable according to the invention;

FIG. 6 represents another type of embodiment of a flexible flat cableaccording to the invention;

FIG. 7 represents schematically a way to use a flexible flat cableaccording to the invention;

FIG. 8 represents in detail a connection mode for a flat flexible cableaccording to the invention;

FIG. 9 represents a first variant of the embodiment of connectors for aflat flexible cable according to the invention; and

FIG. represents a second form of connection for a flat flexible cableaccording to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Before describing the inventionit is suitable to refer to the flexible flat cables existing on themarket.

FIG. 1 represents a very common type of flexible flat cable A. On aflexible support 1 of insulating material shaped like a tape, parallelconductors 2, having a preestablished width, are obtained throughphoto-etching ofa metallic fllm deposited on the flexible support.

In order to avoid oxidizing and degrading of the conductors 2, aprotective insulating film is laid by painting the film on theconductors, or as an alternative a continuous covering tape 3 is appliedusing suitable adhesives. In addition, in order to improve the cableelectric characteristics, a continuous screening metallic. film 4 may beapplied on one or both sides of the flat cable A which in turn may beprotected by a possible insulating sheet 5. The terminal connections areformed for this type of cable by stripping the end of the conductors 2,that is freeing them from the protective sheath, strengthening andpassivating the uncovered terminals of the conductors by means ofelectrolytic plating methods and the subsequent depositing of noblemetals, and bending the so prepared terminal of the cable on aconveniently rigid support, as shown in FIG. 2. The flat cable A is thenblocked on a rigid support 6 by means of suitable clamping devices 7. Aterminal connector which can be inserted in a female connector of thetype used for printed circuit boards, is thus formed by use of the sameflat cable.

Evidently other solutions may also be adopted. For example, theterminals may be soldered to connection pins of connectors of the commontype, having clamping devices for the flexible cable so to avoid themechanical stresses of the soldering points. In all the cases, theconcept followed is always that of a flexible electric connectionelement, obtained from a continuous element with a defined length andprovided, at the terminals only, with convenient devices for electriccontacts. The cable must be prepared and tested in the factory andtherefore the possibility of preparation at the users site is excluded.

FIG. 3 represents another type of flat cable B in which severalconductors 8 with a circular cross section, parallel one to the other,are set on an insulating and flexible support 9. The conductors 8 areclad and maintained in place by an insulating sheet 10 which is made toadhere to support 9 with suitable glues, or with other means or methods.In this case a suitable screening for the cable may be provided for,consisting in general of a metallic grid 11 set on a sheet 10 and inturn covered with an insulating film 12. For this type of flat cable,terminal connectors are used substantially similar to those alreadydescribed. In addition to these, connectors may be used whose connectionbetween the wires and the connector contact elements is accomplished bymeans of an operation, known as crimping.

FIG. 4 illustrates an exploded view of a typical connector for thedescribed flat cable B formed by wires with circular cross section. Theterminal connector consists of an insulating body 13 in which contactpins 14 are inserted terminating at one end with the same number ofpointed forks 15. In the fork's teeth there is an indent which defines around opening having a diameter slightly smaller than the one of thewires to be connected, and the pointed end of the teeth is shaped so toform a guide" for receiving the conductors. The connector is completedby a rigid counterboard l6 having suitable cavities, in each one ofwhich the end of a fork 15 is located after the assembly iscompleted.With suitable control means or jigs the connector body 13 ispressed on the terminals of the flat cable, from which eventually theterminal portion of the screening grid 1 1 has been removed. Due to thisoperation the connector forks 15 punch the insulating sheets 9 and 10each one closes on a conductor insuring the electrical contact. Thecounterboard 16 is clamped on the body of the connector completing it.

The operations to prepare a cable with these types of connectors arevery delicate and require the use of auxiliary devices (the aforesaidjigs") for the correct reciprocal positioning of the parts, and the useof suitable tools for the normal check and tests of the connections.

According to the present invention all of these limitation and theserequirements are overcome with the use of the flat cables of thedescribed preformed types, i.e. prepared with connection means obtainedor applied during the same process of continuous production at a modulardistance one from the other so that cables of the desired length may beobtained on the installation site simply by cutting a continuous cablehaving an undefined length.

FIG. 5 shows in its most simple form a flexible flat cable C accordingto the invention. The physical structure of the cable C is identical tothe one previously described and represented in FIG. 1 but at regularintervals I the covering protective tape presents some openings whichleave the conductors 2C underneath uncovered. In these areas theconductors 2C are plated with noble metals to prevent degrading due tothe atmospheric agents while also obtaining a local strengthening of theconductors themselves. Such a plating operation may be done by acontinuous process during the cable production.

As shown in FIG. 6, when the flat cable also includes a screening orground metallic plane 11D, this also will be provided with openings atregular intervals and of a size slightly exceeding that of the openingin the covering tape for the conductors 8D. In order to allow forpossible connections to the ground plane 11D, the edges of the groundplane near the opening can be plated and left uncovered as shown in FIG.6.

FIGS. 7 and 8 represent a possible method of use for a type of cable asdescribed above.

FIG. 7 represents in its structural assembly'an electronic hypotheticalsystem consisting of several distinct units. The different units aredistributed on a hollow false floor 17, in which the connection cablesamong the various units are laid down and fastened. At regularintervals, the false floor presents suitable openings 18 through whichit is possible to have access to the cables C located internally so thatthe connection areas prearranged on the cables correspond with theseopenings. Through these openings it is possible to make the connectionsbetween the cables and the electronic system units. In all those modularpositions in which no insertion of a unit is planned, the openings areclosed with protective covers.

FIG. 8 represents in detail a particularly suitable method of connectionwithin the false floor. The false floor provides internally on the lowerplane, and in correspondence with every opening, two parallel raisedportions 19 and 20 which define a groove 21 having a suitable width anddepth. The portion of the flat cable in which the conductors areuncovered is inserted and folded in this groove 21. The sides, thebottom and the upper edges of the groove 21 present a slight depressionhaving a width equal to that of the tape, which is used for the correcttransverse positioning of the flat cable. A clamping bracket 22maintains the flat cable in the correct position. The assembly of thefolded flat cable and of the portion of false floor described thus formsa female connector in which it is possible to insert either the terminalrack of a printed circuit board or a connector of equivalent type, asfor example a connector formed with a flexible flat cable as describedin FIG. 2.

The use of a printed circuit board directly for the connection with theflat cable is particularly advantageous where it is necessary to haveconnection circuits of high performance; in fact it is possible toassemble circuits on the board having suitable impedance and circuitsfor line terminations, of suitable impedance, such as to avoidmisadjustments of the line and subsequent reflexions on the transmittedcircuits. FIG. 8 represents a particularly simple connection systemhowever, other solutions may be adopted in accordance with the spirit ofthe present invention.

FIG. 9 shows a second form of the invention which is preferred for theformation of connectors prepared on flat cable. The cable is providedwith openings in the protective film covering the conductors, at regularintervals uncovering suitable portions. On the uncovered part of theconductors two flexible tabs 22 and 23 are applied, consisting of smallportions of a flexible flat cable with conductors at a distance equal tothe distance between the conductors on the cable. The conductors on thetabs 22 and 23 are suitably processed, for example by plating with noblemetals to avoid oxidizing and degrading due to atmospheric agents. Theportions of conductors on the flexible tabs 22 and 23 are each solderedto the corresponding conductor on the cable and form a flexible socketin which a male connector of the type already described may be inserted.On the sides, rigid, suitably shaped 24 and 25 elements (here shown at amutual distance greater than the distance normally used) and cooperatingwith the male connector are provided to insure the necessary contactpressure.

FIG. 10 shows how the same inventive concept may be used with a flatcable D of the type described in FIG.

3. The flat cable D is provided at regular intervals with openings onthe screening grid and in the upper protective film. systematically, incorrespondence to such openings, connectors are applied, of the typealready described in FIG. 4. Male or female connectors are applied atrandom so as to obtain a continuous flat cable provided with a pluralityof connectors at modular distance which may be cut in the requiredlengths on the installation site. In the examples previously described,it is evident that the cable preparation may be accomplished by means ofcontinuous production with the aid of all the tools and simplifiedprocedures which are allowed by mass production, with a continuous checkon the product insuring its quality and reliability.

In the examples previously described it is also evident that for starconnections the cable continuity is not interrupted in any way, and theconnection reliability therefore remains high independent of the numberof connected peripheral units or their connection sequence. It shouldfurther be clear from the foregoing that other changes may be made tothe described invention without departing from the spirit of theinvention itself. For example, in the case of a flat cable with ascreening layerit is not necessary that the openings planned forin theprotection insulating layers be made on the side in which the screeninglayer is located with respect to the assembly of the conductors. Theseopenings may be made on the opposite side, without requiring openings inthe screening conductive 'layer. Similarly, openings may be made on twoopposite sides to allow access, respectively, to the conductor assemblyand to the screening layer, without departing from the spirit of theinvention.

What is claimed is:

l. A female connector intermediate the ends of a flat cable having aplurality of spaced parallel conductors, which comprises a portion ofsaid cable having said insulating material removed to expose saidplurality of conductors and means adjacent said cable portion fonning agroove for receiving a male connector in conducting relation with saidcable, said groove forming means having a pair of parallel spacedelements disposed adjacent the exposed conductors on said cable portionand a pair of flexible tabs having insulating material removed from oneside to expose an equal number of conductors with the same spacing assaid cable conductors, said tabs being positioned with the exposedconductors facing the exposed cable conductors and extending betweensaid spaced elements to provide a conductor between said cable and amale connector when received therebetween, each of said flexible tabscomprise a relatively short length of flexible flat cable.

2. The connector of claim 1 wherein said exposed conductors on each ofsaid flexible tabs is provided with a surface plated with a noble metalto prevent oxidation of said exposed conductors.

a t no: a;

1. A female connector intermediate the ends of a flat cable having aplurality of spaced parallel conductors, which comprises a portion ofsaid cable having Said insulating material removed to expose saidplurality of conductors and means adjacent said cable portion forming agroove for receiving a male connector in conducting relation with saidcable, said groove forming means having a pair of parallel spacedelements disposed adjacent the exposed conductors on said cable portionand a pair of flexible tabs having insulating material removed from oneside to expose an equal number of conductors with the same spacing assaid cable conductors, said tabs being positioned with the exposedconductors facing the exposed cable conductors and extending betweensaid spaced elements to provide a conductor between said cable and amale connector when received therebetween, each of said flexible tabscomprise a relatively short length of flexible flat cable.
 2. Theconnector of claim 1 wherein said exposed conductors on each of saidflexible tabs is provided with a surface plated with a noble metal toprevent oxidation of said exposed conductors.